The present invention relates to an abrasive substrate. More particularly, the present invention relates to a latex-impregnated paper intended for use as an abrasive backing.
The reinforcement of paper by latex polymer impregnation (commonly referred to as latex saturation) is a long-established practice. The polymer employed typically is a synthetic material, most often a latex, and the paper may consist solely of cellulosic fibers or of a mixture of cellulosic and noncellulosic fibers. Polymer reinforcement is employed to improve one or more of such properties as dimensional stability, resistance to chemical and enviromental degradation, resistance to tearing, embossability, resiliency, conformability, moisture and vapor transmission, and abrasion resistance, among others.
Latex saturated papers typically have been used as label print stock, base substrates for abrasive paper, and similar applications where strength is an essential requirement. Currently, backside coatings for abrasive papers provide antislip properties when wet, some degree of water repellency, and perhaps some curl prevention. Nevertheless, there still is an opportunity for improved curl resistance and antislip properties of abrasive backings and papers.
The present invention addresses some of the difficulties and problems discussed above by providing a curl-resistant, antislip abrasive backing which includes a polymer-reinforced paper having a first surface and a second surface; a synthetic polymeric layer bonded to the first surface; and an amorphous, rubbery polymer film layer bonded to the second surface.
The present invention also provides a curl-resistant, antislip abrasive paper which includes a polymer-reinforced paper having a first surface and a second surface; a synthetic polymeric layer bonded to the first surface; a layer of abrasive particles bonded to the synthetic polymer layer; and an amorphous, rubbery polymer film layer bonded to the second surface.
By way of example only, the amorphous, rubbery polymer may be a polyester elastomer. As another example, the amorphous, rubbery polymer may be an amorphous, rubbery polypropylene. Additional examples include polyurethenes and polyethers. For example, the polymer may be a polyetherester, such as Arnitel(copyright) EM400, which polymers are described more fully in, e.g., U.S. Pat. No. 4,707,398 to Boggs, which patent is incorporated herein by reference in its entirety. Amitel(copyright) EM400 is available from A. Schulman of Akron, Ohio, or Akzo Plastics of Arnhem, Holland.
As used herein, the term xe2x80x9cbackside layerxe2x80x9d refers to a layer or coating on the backside of an abrasive paper, i.e., the side of the abrasive paper which does not have the layer of abrasive particles thereon.
The term xe2x80x9cabrasive backingxe2x80x9d is used herein to mean a paper, typically a polymer-reinforced paper, which is intended to be provided with a layer of abrasive particles. The term xe2x80x9cabrasive paperxe2x80x9d refers to the combination of an abrasive backing and a layer of abrasive particles.
As used herein, the term xe2x80x9cpaperxe2x80x9d is meant to include any web or sheet-like material which contains at least about 50 percent by weight of cellulosic fibers. In addition to cellulosic fibers, the web may contain other natural fibers, synthetic fibers, or mixtures thereof. Cellulosic nonwoven webs may be prepared by air laying or wet laying relatively short fibers to form a web or sheet. Thus, the term includes sheets prepared from a papermaking furnish. Such furnish may include only cellulose fibers or a mixture of cellulose fibers with other natural fibers and/or synthetic fibers. The furnish also may contain additives and other materials, such as fillers, e.g., clay and titanium dioxide, surfactants, antifoaming agents, and the like, as is well known in the papermaking art.
As a practical matter, the abrasive paper of the present invention will be prepared from a latex-impregnated paper. By way of illustration only, the latex-impregnated paper may be a water leaf sheet of wood pulp fibers or alpha pulp fibers impregnated with a reactive acrylic polymer latex such as Rhoplex(copyright) B-15 (Rohm and Haas Company, Philadelphia, Pa.). However, any of a number of other latices may be used, if desired, some examples of which are summarized in Table A, which follows.
The impregnating dispersion typically will contain clay and an opacifier such as titanium dioxide. Exemplary amounts of these two materials are 16 parts and 4 parts, respectively, per 100 parts of polymer on a dry weight basis. By way of example only, the first layer may have a basis weight of 13.3 lbs/1300 ft2 (50 g/m2) before impregnation.
The impregnated paper generally may contain impregnant in a range of from about 5 to about 50 percent by weight, on a dry weight basis, although in some cases higher levels of impregnant in the paper may be suitable. As an illustration, the paper may contain 18 parts impregnating solids per 100 parts fiber by weight, and may have a basis weight of 15.6 lbs/1300 ft2 (58 g/m2), both on a dry weight basis. A suitable caliper is 3.8xc2x10.3 mil (97xc2x18 micrometers).
As already stated, the curl-resistant, antislip abrasive backing of the present invention includes a polymer-reinforced paper having a first surface and a second surface; a synthetic polymeric layer bonded to the first surface; and an amorphous, rubbery polymer film layer bonded to the second surface.
The curl-resistant, antislip abrasive paper of the present invention includes a polymer-reinforced paper having a first surface and a second surface; a synthetic polymeric layer bonded to the first surface; a layer of abrasive particles bonded to the synthetic polymer layer; and an amorphous, rubbery polymer film layer bonded to the second surface.
By way of example only, the amorphous, rubbery polymer may be a polyester elastomer. As another example, the amorphous, rubbery polymer may be an amorphous, rubbery polypropylene.
The amorphous, rubbery polymer film layer in general may be formed on the second surface of the paper by melt-extrusion or extrusion-casting techniques which are well known to those having ordinary skill in the art. Alternatively, a preformed film of the amorphous, rubbery polymer may be bonded to the second side of the paper, again by known means.
In general, the amorphous, rubbery polymer film layer may be of any desired thickness, depending upon the requirements of the abrasive paper. For example, the amorphous polymer film layer may have a thickness of from about 0.2 to about 3 mils (from about 5 to about 75 micrometers). As another example, the amorphous polymer film layer may have a thickness of from about 0.5 to about 1 mil (from about 12 to about 25 micrometers).
The present invention is further described by the example which follows. Such example, however, is not to be construed as limiting in any way either the spirit or the scope of the present invention.